Mephisto is a demon and a major antagonist in the Marvel Comics universe, particularly known for his dealings with heroes such as Spider-Man, Ghost Rider, and Doctor Strange. He is often depicted as an embodiment of selfish desires, manipulating mortals into making pacts that ultimately serve his own designs. His origin hails from the realms of Hell, where he rules as a powerful entity. His earliest appearance was in 'The Amazing Spider-Man' #14 in 1964. Over the years, Mephisto has established a reputation not only as a cunning adversary but also as a complex character who occasionally aids heroes if it serves his interests. Additionally, Mephisto's stories typically revolve around themes of morality, sacrifice, and the nature of evil itself. He seeks to claim the souls of deserving individuals, and his schemes often throw characters into moral dilemmas, challenging their heroes' principles. His influence extends across multiple story arcs, showcasing his interactions and entanglements with various Marvel characters through the decades.